The optically anisotropic layer is formed by aligning a discotic liquid crystalline compound (disc-like liquid crystalline compound) and fixing the aligned state. The discotic liquid crystalline compound generally has a large birefringence. Also, the discotic liquid crystalline compound has various aligning modes. When a discotic liquid crystalline compound is used, a retardation plate having optical properties unobtainable by a conventional stretched birefringent film can be produced.
In order to use the liquid crystalline compound for a retardation plate, the entire molecules constituting the optically anisotropic layer must be uniformly aligned, that is, the discotic liquid crystalline compound is preferably oriented in a monodomain alignment. However, conventional discotic liquid crystalline compounds are oriented in a dual-domain alignment and this causes generation of alignment defects at the boundary of domains. Therefore, in many cases, conventional discotic liquid crystalline compounds cannot assure optical properties necessary for the application to a retardation plate. The optical properties are dependent on the chemical structure of the discotic liquid crystalline compound. In this respect, as described in Molecular Crystals and Liquid Crystals, Vol. 370, page 391 (2001), many kinds of discotic liquid crystalline compounds have been studied and developed so as to obtain necessary optical properties.
However, there is a demand for a retardation plate having an optically anisotropic layer formed from a discotic liquid crystalline compound having a wavelength dispersion property lower than that of discotic liquid crystalline compounds known at present.